RX J2130.6+4710 – an eclipsing white dwarf–M-dwarf binary star

摘要: We report the detection of eclipses in close white-dwarf-M-dwarf binary star RX J2130.6+4710. present light curves B, V and I bands fast photometry obtained with three-channel CCD photometer Ultracam eclipse u � , gand rbands. The depth varies from 3.0 mag uband to less than 0.1 band. times mid-eclipse are given by ephemeris BJD(mid-eclipse) = 2 452 785.681 876(2) + 0.521 035 625(3) E, where figures parentheses denote uncertainties final digit. medium-resolution spectroscopy which we have measured spectroscopic orbits M dwarf white dwarf. estimate that spectral type is M3.5Ve or M4Ve, although data on this based not ideal for classification. compared spectra synthetic pure hydrogen model atmospheres effective temperature T eff 18 000 ± 1000 K. used width primary duration totality precisely udata combined amplitude ellipsoidal effect band semi-amplitudes derive masses radii has a mass 0.555 0.023 Mand radius 0.534 0.053 R� typical stars mass. 0.554 0.017 its 0.0137 0.0014 expected carbon-oxygen tem- perature. affected frequent flares associated dark spots surface can be detected distortions radial velocities. J2130.6+4710 rare example pre-cataclysmic variable will start transfer at period above gap cataclysmic variables. Ke yw ords: binaries: - eclipsing stars: fundamental parameters individual: dwarfs.